Method of producing insecticides



Filed Aug. 18, 1930 593m R. w.. IIJ .Illv u zmmw mf .M Y \I E ,PR ozuxm wf m I 1 .M MA pv rw /j JW, MONw( Q m M526. `Y M B m Ej@ m @zio/Em i A a; 5.2mm Z L For moli m\\ 02C m1 5 m\ m2 Qz mao Iu Tx El man o S YPatented Aug. 29, 1933 A 'UNITED STATES PATENT V0l ''F.lLClI-I; y 1,924,518 f i V i y METHOD oF PRODUCING` INsac'rlcmas Eugene R. Rushton, .Montgomerm Ala.

Application August 18, 1930; Serial No.1f176',1`73

claims. (C1. :z3-'53) Y y The present invention has to do with a new pure dust'from smelters or roasting furnaces. can. and improved process of producingarsenic combe used as rawV materials and calcium Yarse'nate pounds, and particularly those arsenates which may be produceddirectly from unrelined arseni-v have been found of great utility as insecticides. cal dust. Y 1

My invention will -be illustrated in terms of .In the matter of heat source 4and.conservation' calcium arsenate production. but it is to bedisof the same,I -nd'lthat it is .preferable to use a tinctly understood that barium, magnesium'and gaseous fuel in'my `process and tha-t in Vorde;` .to lead arsenate may be prepared in an entirely conserve the heat generated in the process, itlis analogous manner. In. preparing calcium aryadvisable to passthe arsenical vapors in heat ex- W "il, senate, calcium oxide, limestone or chalk is blown change relationship with the hot product coming intoareaction chamber containing arsenical vafrom the reacting fiue as indicatedin .the drawpors, in the form of a dust stream. 'Ihat is to ing, I l say the Ychalk or equivalent compound, is blown `As regards the source of chalk or limestone, it n into-the reaction zone in the vform -of a very light may `be stated that various grades of the same 15 powder, whence a very intimate `contact between from various sources may be used. lThus, Vfor n: the said chalk or equivalent compound and the example, the chalkproduced as a by-productin arsenical vapors is attained. the causticization of sodiumA carbonate vor in In order to Imore readily explain the theory of the manufacture of 85 per cent magnesiafmay operation of my novel process for preparingcalbe used. If the chalky has a small amount of "2 cium arsenate, it may be said that my process insodium salts associated therewith, no deleteri n volves a practical application of a broad princi- Nous effect is produced in the nal product but ple enunciated by Simon in 183.7 (Poggendorf Von the contrary a benet accrues to the final Ann. 40, p. 417).' Simon found when calcium `product .since the slight hygroscopicty thereby arsenite is heated in the absenceof air, calcium produced as aresult of traces of sodium, salts `arsenate and elementary arsenic are formed. or even free caustic soda imparts a slight moistgg I'he tendency to form arsenate is so great that ening effect on the product afterA it is dusted part of the arsenious oxide combined with the yon the plants land hence it tends to function lime is reduced to .supply the oxygen necessary to as an'adhesive` and thereby lessen .the tendency oxidize `the remaining `arsenious. oxide `to the of 'the Apowder to `be shaken off `the plants, if 3G pentoxide.` Of course, when air is present, the they are blown by Wind.

arsenic is re-oxidized to the trioxide, some of My process may be carried'out in numerous which escapes as vapor. I have found that 'if types of apparatus and.v the V embodiment illus,- chalk, for example be previously heated to such trated by the accompanying drawingis merely a degree that-the vapor pressure of the ycarbon diagrammatic and specific details will be readily '55 dioxide content fof the chalk is nearly equal to apparent to one skilledin the art. u j c6 one atmosphere and thisfchalk is introduced into Referring specifically to the accompanying a reaction chamber inV the form of an airsusdrawing, air and fuel `are introduced into `the pension or dust stream, that it will form with `heatingflue 2 until the heating flue reaches the arsenious oxide vapors and air therein contained,` desired temperature which is between 800 V to 40 ra very satisfactory form of calcium arsenate. 1000 C., when the fuel-'supply isreduced or cutv 95 That is to say,the calcium arsenate is inthe off completely. Chalk dust and air are then form of a light,` iluy powder which can readily blown into the heating ue 2, the 'air having be blown out of a dusting machine such as that been .previously preheated by passage through 1 `commonlyused in dusting cotton `plants `with an heat exchanger k7. The chalk dust and air then j insecticide, on-to theplant. I l pass into the` reacting flue 4, meanwhile` crude 1D0 'As regards` the source of arsenic, I may use arsenic is fed into the reacting `flue vviathe heat either metal arsenic or arsenious oxide (the white exchanger 7 wherein it is vvaporized: Due to arsenic of commerce) `.asa starting materiaLfbut the, stream of air laden with chalk dust as it I have found that, in order to insure that no imenters, and calcium arsenate as it leaves the purities will appear in the final product that, reacting flue, an injector effect or suction draws `l5 it is advisable to vaporize the arsenic `or arthearsenical vapors into the said reacting flue. senious oxide in a chamber prior to its'introduc- The amount ofv air passed through the reacting tion into the reaction zonesince non-volatile imfiue is in excess of that required for theroxidapurities are thus left behind in the vaporzing tion of the arsenious oxide to arsenate, this exchamber. Consequently, by this method, imcess being about 30%. The chemical reaction 0 taking place in reacting flue 4 may be representedvby the following chemical equation:

Vchanger V'7 which in reality is also a vaporizer lfor the arsenious oxide,` any known' type may b'e Y used. Thus, the heat ,exchangery may be of very simple construction comprising two concentric tubes in the inner of which the stream of calciuml arsenate laden air is passed while crude arsenic is fed into the tcp ofthe outer tube and as it descends it receives heat from the v`said innertube and isfvaporized. In this latter vaporisation step, of course, non-volatile vimpurities will vfall to the'bottom` of the said outer tube and maybe withdrawn from'time totime as the occasion may arise. In the accompanying diagrammatic sketch incoming air islpreheated'in the heat exchanger 7. In order to accomplish this the above two tube heat exchangercouldbe supplanted' by-a three tube exchanger, the inner tube being of comparatively small diameter and serving as a conduitror the incoming air,`the hot dust stream thus-serving a doublerfuncticn of preheating incoming lair 4and' vaporizingv arsenical vapors.

As may be readily seen from the accompanying drawing fans or blowers are used to maintain a constant circulation of air. If it' so happens that the chalk requires grinding this may be done by'crushing rollers'or similar device. 'Ihe chalk dustmay preferably be introducedV into chamber 3 tangentially tothe di- 'rection of the incoming current of heated air whence'it isV swept into heating nue 2. The supply of "chalk" entering chamber 3 should vbe -so regulated that substantially all of it is swept forwardly Vand consequently none of Yit isv allowed to settleto the bottom of the chamber. The entire system may be provided with dampers at'any convenient point by means of which theair'stream may be controlled inv any desired manner. .f

" By ay dust streamfI solid'in a current of air.

As used in the'Y claims, an excess of oxygen mean a suspension of a signifies that the amount present is greater than that. requiredv for the .oxidation of arsenical,

vapor tothe pentavalent oxide.

' VAs used in the claims,arsem'cal vapor includes metallic arsenic and oxides thereof.

It is to `be distinctly understood that I do not limit Ymyself to the specic details mentioned 651 herein, but include as part of my invention all modications thereof as may reasonably fall Vwithin'th'e'scope of the appended claims.

I What I claim is:

1. `The process of producing' insecticides which comprises reacting arsenical vapors and an oxygenated compound of the group consistingY oi' calcium, barium, magnesium, and lead, the said compoundbeing in the form of a dust stream.

2. The process of producing insecticides which comprises reacting arsenical vapors and a carbonate of a metal selected from thegroup consisting of calcium, barium, magnesium, and lead,

the-said carbonate' being in the form of` a dust` stream.

3. .A process for preparing calcium arsenate comprising reacting arsenical vapors and a compOund selected from the group consisting of .calcium oxide, calcium hydroxide, and calcium carbonate, the latter being in the form of a dust stream. v v

4. A process Y for preparing calcium arsenate comprising reacting arsenical' vapors and calcium carbonate in the form of a dust stream.

5. A process for preparing calciumY arsenate comprising reacting arsenical vapors and calcium 'carbonate in the formlof a Vdust streamandn the presence of an excess of oxygen.l

6. A process for preparing calcium arsenate Vccmprising reacting arsenical vapors "and calkciurn carbonate inthe form of a duststream'and in the presence of excessvoxygen and heat. f

'LA process for preparing, calciumarsenate whichk comprises reacting arsenic in the form of a vapor and calcium carbonate in the form of a dust stream in the presence of excess oxygen.'

8.' A process for preparing calcium arsenate v which comprises reacting arsenious oxide in the form ofa vapor and calcium carbonate in the formof a dust stream in the presence o f' excess oxygen and heat. f V.

9.A process for preparing calcium arsenate which comprises reactingarsenious oxide and calcium oxide in the form `of a vdust stream.

v10. A process'for preparing vcalcium arsenate which comprises reacting arsenious oxide in the form ofra vapor and calcium oxide in the form of a dust stream. f

' r -11. A'fpr'ocess for preparing calcium arsenate W ich comprises reacting'arsenious oxide in the form'of a vapor-'and calciumv oxide in the form of a dust streamfin the presence of excess oxygen. L y

12.-A pr'ocess'lfor preparing calcium arsenate.

which comprises reacting arsenious oxide inthe formof avapor and calcium oxide .in the form of a dust stream in the presence of excess oxygen and heat.

V13. A process! fcrfpreparing calcium arsenate which comprises reacting arsenious oxide vapors and calcium` carbonate inthe form of a dust stream'at temperatures between 800 to'100 0 C.

14. A process for preparing calcium arsenate f which comprises reacting arsenicalvapors rand calcium carbonate in the form of a dust stream at temperatures between 800 and 1000"' C.V y

l l5. A process for preparing calcium arsenate which comprises reacting arsenical vapors and calcium 'carbonate'in theform of afdust stream at temperatures between 800 CL and 1000 C.,in.

the presence of excess oxygen.

EUGENE E. RUsnroNt 

